Bulletin of the American Physical Society
17th Biennial International Conference of the APS Topical Group on Shock Compression of Condensed Matter
Volume 56, Number 6
Sunday–Friday, June 26–July 1 2011; Chicago, Illinois
Session Y1: High Pressure Strength VI |
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Chair: Robert Rudd, Lawrence Livermore National Laboratory Room: Grand Ballroom I-III |
Friday, July 1, 2011 9:15AM - 9:30AM |
Y1.00001: Dynamic strength measurement using magnetically applied pressure shear (MAPS) C.S. Alexander, J.R. Asay, T.A. Haill A newly developed experimental technique to measure dynamic material strength at high pressures on magneto-hydrodynamic (MHD) drive pulsed power platforms is demonstrated on aluminum. The application of an external magnetic field normal to the plane of the MHD drive current directly induces a shear stress wave in addition to the usual longitudinal stress wave. Strength is probed by passing this shear wave through the sample material where the transmissible shear stress is limited to the sample strength. The magnitude of the transmitted shear wave is measured via a transverse VISAR system from which the sample strength is determined. Details of the experimental approach will be presented along with results of initial experiments on 99.5{\%} pure aluminum which demonstrate the utility of the technique. [Preview Abstract] |
Friday, July 1, 2011 9:30AM - 9:45AM |
Y1.00002: Strength and Micro-strain Distribution of Shock Compressed Aluminum Single Crystals Determined from Real-time X-ray Diffraction Stefan Turneaure, Y.M. Gupta Shock compressed Al(100) single crystals were examined using x-ray diffraction (XRD) and velocity interferometry. Mo K$\alpha $ x-rays were used to obtain high resolution XRD measurements of the Al 200, 400, and 600 peaks. The XRD measurements were obtained at the rear surface of the Al after a partial stress release due to reflection of the plastic wave at an Al/vitreous carbon interface. Analytic methods were developed to determine macroscopic strength and local micro-strain distributions from XRD measurements and were applied to the Al(100) XRD data. The Al crystals are shown to strain harden; for the highest stress experiment (12.7 GPa Al input stress and 7.1 GPa reflected stress), the strength is 0.52 GPa compared to a strength of 0.025 GPa at the HEL. The distribution of local micro-strains is used to estimate the distribution of local maximum stress differences. The FWHM of the distribution of local maximum stress differences is about 50{\%} of the macroscopic stress difference (or strength) for shock compressed Al(100). Work supported by DOE/NNSA. [Preview Abstract] |
Friday, July 1, 2011 9:45AM - 10:00AM |
Y1.00003: Using in situ x-ray diffraction measurements to study dynamic strength in shock loaded materials Hector Lorenzana, James Hawreliak, Jon Eggert, Ryan Rygg, James McNaney, Gilbert Collins, Andrew Higginbotham, Justin Wark One of the outstanding questions in understanding the shock and high strain rate response of materials is how they plastically relax on timescales relevant to dynamic loading processes (nanoseconds), or the dynamic strength of the material. In situ x-ray diffraction can offer unique insight into material response, particularly when it is used to make measurements during high strain rate compression. Using a particular experimental geometries can allow measurements of the elastic component of strain transverse and parallel to the shock direction for grains of more then one orientation during the relaxation process. We present in situ x-ray diffraction measurements of shock compressed rolled iron foils where there is a measurable deviation from hydrostatic compression. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. [Preview Abstract] |
Friday, July 1, 2011 10:00AM - 10:15AM |
Y1.00004: ABSTRACT WITHDRAWN |
Friday, July 1, 2011 10:15AM - 10:30AM |
Y1.00005: Approaching the Ultimate Shear and Tensile Strength of Aluminum in Experiments with Femtosecond Laser Pulses Sergey Ashitkov, Mikhail Agranat, Gennady Kanel, Vladimir Fortov We studied the shock-wave phenomena generated by femtosecond laser pulses in aluminum films with thicknesses from 0.5 to 1.2 microns. The free surface displacement as a function of time has been measured with ultrafast time-resolved interferometric microscopy and converted into the free-surface velocity history. The relation between the shock front velocity and the particle velocity indicates the shock compression remains elastic at least up to 13 GPa under these conditions. Shear stresses reached 3.4 GPa, which is close to estimated ultimate value for aluminum. The observed elastic shock wave results in the small ($\le $1 ps) rise time of the shock fronts. The data are in excellent agreement with dependence of apparent Hugoniot elastic limit on the wave propagation distance in the plate impact experiments. The spall strength of aluminum at strain rates of about 10$^{9}$ s$^{-1}$ is comparable with its ultimate tensile strength of perfect Al crystal and is in good agreement with molecular dynamics calculations. [Preview Abstract] |
Friday, July 1, 2011 10:30AM - 10:45AM |
Y1.00006: Effects of Rock High Pressure Strength on Penetration Hongfa Huang Perforating of oil/gas well creates communication tunnel between reservoir and wellbore. Shaped charges are widely used as perforators in oilfield industry. The liners of the charges are mostly made of powder metal to prevent solid slug clogging the entrance hole of well casing or locking the hole in perforating gun. High speed jet from the shaped charge pierces through perforating gun, well fluid, well casing, and then penetrates into reservoir formation. Prediction of jet penetration in reservoir rock is critical in modeling of well production. An analytical penetration model developed for solid rod by Tate and Alekseevskii is applied. However, strength of formation rock at high pressure needs to be measured. Lateral stress gauge measurements in plate impact tests are conducted. Piezoelectric pressure gauges are imbedded in samples to measure the longitudinal and transverse stress. The two stresses provide Hugoniot and material compressive strength. Indiana limestone, a typical rock in perforation testing, is selected as target sample material in the plate impact tests. Since target strength effect on penetration is more significant in late stage of penetration when the strength of material becomes significant compared to the impact pressure, all the impact tests are focused on lower impact pressure up to 9 GPa. The measurements show that the strength increases with impact pressure. The results are applied in the penetration calculations. The final penetration matches testing data very well. [Preview Abstract] |
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